Miniaturized differential pressure switch with integral contact and spring mounted on diaphragm

ABSTRACT

A miniaturized differential pressure switch comprising a pair of matched housing sections and a low spring rate diaphragm of quadrilateral shape in the plane of the housing sections secured together by rivets at their corners, with the housings being recessed about on either side of the diaphragm to define high and low fluid pressure chambers of restricted depth that are adapted to be connected to differential gas pressure sources, in which the housing section that defines the low pressure chamber is equipped with electrical contacts disposed in the low pressure chamber, and the low pressure chamber has mounted in same a diaphragm plate that serves to close the switch contacts at the desired pressure differential, which diaphragm plate is equipped with a tongue acting as a range spring that is adjustable exteriorly of the housing by way of an adjusting screw that is threadedly mounted in the housing and that has its inner end journaled in an end portion of the tongue. The switch is adapted for use in connection with gas pressures of under 5 psig.

United States Patent [1 1 Phillips et al.

[ MINIATURIZED DIFFERENTIAL PRESSURE SWITCH WITH INTEGRAL CONTACT AND SPRING MOUNTED ON DIAPHRAGM [75] Inventors: James W. Phillips, Michigan City; Richard S. Zoludow, South Bend,

both of Ind.

[73] Assignee: Dwyer Instruments, Inc., Michigan City, Ind.

[22] Filed: Dec. 17, 1973 211 Appl.,No.: 425,267

[52] US. Cl 200/83 N, 200/83 S, 2 00/83 N [51] Int. Cl. H0lh 35/34 [58] Field of Search.... 200/83 R, 83 .A, 83 N, 83 P,

' 200/83 S, 83 T, 83 V, 83 W [451 Jan. 21, 1975 Primary Examiner-Robert K. Schaefer Assistant ExaminerGerald P. Tolin Attorney, Agent, or FirmMann, Brown, McWilliams & Bradway [57] ABSTRACT A miniaturized differential pressure switch comprising a pair of matched housing sections and a low spring rate diaphragm of quadrilateral shape in the plane of the housing sections secured together by rivets at their corners, with the housings being recessed about on either side of the diaphragm to define high and low fluid pressure chambers of restricted depth that are adapted to be connected to differential gas pressure sources, in which the housing section that defines the low pressure chamber is equipped with electrical contacts disposed in the low pressure chamber, and the 'low pressure chamber has mounted in same a diaphragm plate that serves to close the switch contacts at the desired pressure differential, which diaphragm plate is equipped with a tongue acting as a range spring that is adjustable exteriorly of the housing by way of an adjusting screw that is threadedly mounted in the housing and that has its inner end journaled in an end portion of the tongue The switch is adapted for use in connection with gas pressures of under 5 psig.

10 Claims, 9 Drawing Figures Patented Jan. 21, 1975 3,862,387

2 Sheets-Sheet 2 80 mmg 1 MINIATURIZED DIFFERENTIAL PRESSURE SWITCH WITH INTEGRAL CONTACT AND SPRING MOUNTED ON DIAPHRAGM This invention relates to a miniaturized differential pressure switch, and more particularly, to a differential pressure switch of small proportions that is adapted for use in connection with pressures below psig.

Miniaturizing differential pressure switches for low pressure applications requires that the basic switching components and sensitivity be retained while providing readily adaptable for miniaturized low pressure differential switch applications.

A principal object of the invention is to provide a miniaturized differential pressure switch that is especially adapted to be of the miniature switch type.

Another principal object of the invention is to pro vide miniaturized differential pressure switch that is reduced to a minimum of separate parts, and in which the diaphragm plate and range spring therefor are of special one-piece construction.

Other objects of the invention are to provide a miniaturized differential pressure switch of simplified construction that is economical of manufacture, convenient to use, and long-lived in operation.

In accordance with this invention, a miniaturized differential pressure switch is provided comprising a pair of matched housing sections formed from a suitable plastic material, and a low spring rate type diaphragm, in which the housing sections and diaphragm are of quadrilateral shape in the plane of the housing sections and are secured together by rivets at their corners. The housing sections are recessed a restricted amount on either side of the diaphragm to define high and low pressure chambers of restricted depth, with the housing sections being formed to connect the respective chambers to differential gas pressure sources. The housing section that defines the low pressure chamber is equipped with a pair of spaced apart electrical contacts disposed in the low pressure chamber, and the low pressure chamber has mounted in same a special diaphragm plate that seats against the diaphragm and is equipped with atongue that acts as a range spring which is adjustable through an adjusting screw that is .threadedly mounted'in the housing to extend into the low pressure chamber, with the inner end of the adjustment screw being journaled in an end portion of the tongue.

The high and low pressure chambers are round in outline, as is the diaphragm plate, and the diaphragm plate tongue includes a tab that is placed in keying relation with the housing to hold the diaphragm against rotational shifting movement within the low pressure chamber.

The range spring adjustment screw is'socketed for application thereto of a suitable turning tool from the exterior of the housing whereby the adjustment screw may be adjusted to set the diaphragm plate against the diaphragm as required so that a predetermined pressure differential will cause the diaphragm to seat the diaphragm plate against the switch contacts to close the switch.

Other objects, uses, and advantages will be obvious or become apparent from a consideration of the following detailed description and the application drawings.

In the drawings:

FIG. 1 is an elevational view of one embodiment of the invention;

FIG. 2 is a plan view of the low pressure end of the housing, the view of FIG. 2 being taken from the top of FIG. 1 and rotated counterclockwise degrees;

FIG. 2A is a fragmental sectional view taken substantially along line 2A2A of FIG. 2;

FIG. 3 is a sectional view taken substantially along line 3-3 of FIG. 1, but on an enlarged scale;

FIG. 4 is a sectional view taken substantially along line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken substantially along line 5-5 of FIG. 2;

FIG. 6 is a plan view of the switch diaphragm;

FIG. 7 is a plan view of the switch diaphragm plate;

and

FIG. 8 is an edge view of the diaphragm plate taken substantially along line 8-8 of FIG. 7.

However, it is to be distinctly understood that the specific drawing illustrations provided are supplied primarily to comply with the requirements of the Patent Laws, and that the invention may have other embodiments that will be obvious to those skilled in the art, and which are intended to be covered by the appended claims.

Reference numeral 10 of FIGS. 1 4 generally indicates a preferred embodiment of the invention which comprises a housing 12 comprising a low pressure housing section 14 and a high pressure housing section 16, a low spring rate diaphragm 18 (see FIG. 3), a diaphragm plate 20 equipped with a range springdefining tongue 22, an adjustment screw 24 threadedly mounted in the housing 12 in operative association 'with the diaphragm plate tongue 22, and a pair of electricaal contacts 26 adapted to be closed by the diaphragm plate 20 at the desired pressure differential, which contacts 26 are respectively operatively connected to the respective electrical connectors 28 and 30.

The housing sections 14 and 16 are in face to face relation, and the sections 14 and 16 and the diaphragm 18 are of matching quadrilateral configuration so that these parts may be assembled together by aligning their respective corner openings 27, 29 and 31 to receive suitable tubular rivets 32 (see FIG. 2A).

The housing sections 14 and 16 are formed with the respective circular recesses 34 and 36 (of substantially equal diameters), that are of limited depth, so that they define a diaphragm chamber 38 across which is applied the diaphragm 20 that has its margin 40 disposed between the rim portions 42 and 44 of the respective housing sections 14 and 16. The housing section 16 is formed with an upstanding sealing ridge 46 (see FIG. 3) that is in unbroken circumambient relation about the recess 36 to effect a good fluid tight seal about the diaphragm when the housing sections are clamped together under the action of applying the rivets 32.

The diaphragm 18 defines the diaphragm chamber 38 into a high pressure chamber 50 and a low pressure chamber 52. Housing section l6is shaped to define tubular portion 54 providing a bore 56 communicating atmosphere or connected to a source of low pressure by applying a suitable flexible tubular member to the projecting end 68 thereof.

Received within the low'pressure chamber 52 is diaphragm plate 20 (see FIGS. 7 and 8) that has special significance. Plate 20 generally comprises a disc 72 formed from electrically conducting material, such as copper, and formed to define a round margin 74, and a tongue portion 76 that is defined from the mid portion of same, and which projects outwardly of same. The tongue 76 thus comprises a struck out section 78 of the disc 72 that comprises angled or diagonal portion 80, and end portion 82 that is disposed generally parallel to the plane of the disc 72 that is. formed with aperture 84 and an upstanding tab 86. Struck out section 78 leaves opening 87 in plate 72.

In accordance with this invention, the diaphragm plate 72 has operably associated therewith the adjusting screw 24 (see FIG. 3), which defines a head end 90 (see FIG. 3) formed with a stud 92 that is received in the tongue opening 84 for purposes of journaling the screw 24 of the diaphragm plate. The screw stud 92 is suitably pressed formed as at 94 to rotatably mount the stud 92 within the opening 84 for journaling purposes. Screw 24 also comprises shank 96 that is threaded as at 98 for cooperation with threading 100 of opening 102 formed in the housing section 14 for this purpose. The shank-96 of screw 24 is socketed as at 104 in a hex shape or the like to receive the shank of a suitable turning tool to move the screw 24 relative to the housing section 14 for adjustment purposes. Housing section 14 is bossed as at 106 so that the shank end of the screw 24 is recessed within the housing section 14.

As indicated in FIG. 3, the diaphragm plate 20 is ap plied to chamber 52 so that'the side 108 of the disc 72 bears against the side 110 of the diaphragm 18, with the shank of the adjustment screw 24 being placed in threaded relation with the threading 100 of housing opening 102. The housing section 14 is recessed as at 112 to receive the tab 86 of the diaphragm plate tongue 76 to key the diaphragm plate against rotational movement relative to the housing 12 (which movement would tend to change the adjustment of the screw 24).

The housing section 14 on either side of the boss 106 has mounted in same the contacts 26 that are operably associated with the respective connectors 28 and 30.

The contacts 26 extend into the low pressure chamber 52 (see FIG. 5., which is illustrative of both contacts 26, even though only one is shown) for contact by the diaphragm plate 20 at points on either side of the diaphragm plate tongue 76. In the form shown, the contacts 26 are in the form of rivets 120 having their heads 122 disposed within the chamber 52 and their shanks 1 24 extending through housing openings 126 for application to the respective connectors 28 and 30. The connectors 28 and 30 each comprise an angle shaped terminal member 130 having a base arm 132 apertured as at 134 to receive the respective rivet shanks 124, and an upright arm 136 shaped and apertured as may be necessary or desirable for connection thereto of suitable leads. The members 130 are held in place by the rivet shanks 134 being riveted over against washers 138.

The connector members 130 are seated within a low three sided centering wall 140 that holds the respective members 130 from rotation.

The housing sections 14 and 16 may be formed from a suitable plastic compound by employing suitable molding procedures. Examples are fiberglass filled polycarbonate, acetals, and acrylonitrile butadiene styrene.

The diaphragm 18 comprises a sheet of suitable wear resisting elastomeric material (such as polyurethane) given the generally quadrilateral shape that is shown in FIG. 6.

The housing section 14 at each of its rivet receiving openings 27 is formed with a short annular extension 141 (see FIG. 2A) that is received in counterbore 142 of the housing section 16, whichcounterbores 142 are formed about the respective rivet receiving openings 29 of the housing section 16. The diaphragm 18 has its corner openings 31 proportioned to closely receive the projections 141 to facilitate assembly of the device, whereby the diaphragm 18 is readily correctly aligned relative to both of the housing sections.

Assuming that theswitch 10 is wired into the desired circuit, and the tubular portions 54 and 64 of the respective housings have been connected to the sources of gas under pressure as required, the range spring formed by diaphragm plate tongue 76 maintains the diaphragm plate 20 spaced from the contacts 26 until the pressure in the high pressure chamber 50 exceeds a predetermined desired amount, whereupon the pressure differential acting on the diaphragm 18 brings the diaphragm plate 20, against the bias exerted by tongue 76, into contact with the contacts 26 to close the circuit that is involved, through the switch 10. Of course, switch 10 can be used to open the circuit as well as close it, by appropriate control of the gas pressures available to the respective chambers 50 and 52.

In conformity with the miniaturizing approach that the invention takes, the housing recesses 34 and 36 are of restricted depth for minimizing the volume of the high and low pressure chambers of the device. The housing section 16 is formed with protuberances at spaced points thereabout to hold the diaphragm 18 spaced from the floor surface 162 of recess 36 to insure that all of the area of the diaphragm on its side 111 that is disposed within the chamber 50 is exposed to the high pressure source.

The differential pressures sensed may be between two positive pressures, two negative pressures, a positive pressure and atmospheric pressure, and atmospheric pressure and a negative pressure, depending on the application. The pressure source connected to chamber 52 should be the lower pressure of the differential to be sensed. Also, the high pressure chamber 50 is adapted to accommodate liquids and thus may be connected to liquid pressure sources.

The invention as disclosed is particularly suited for use in connection with low current electronic circuitry such as might be found in connection with computer equipment or the like for control purposes. However,

the general arrangement involved may be readily adapted for other applications, and specifics such as the quadrilateral configuration of the housing sections l4 and 16 and diaphragm 18, the use of rivets to hold merely to explain and illustrate the invention and the invention is not to be limited thereto, except insofar as the appended claims are so limited, since those skilled in the art who have the disclosure before them will be able to make modifications and'variations therein without departing from the scope of the-invention.

We claim:

1. In a differential pressure switch of the type including a housing having a diaphragm therein defining with said housing fluid pressure chambers on either side of said diaphragm of restricted depth, with said housing defining bores in communication to separate sources of fluid pressure, and an electrically conductive diaphragm plate received in one of said chambers and seated on one side thereof against said diaphragm, with the housing portion that defines said one chamber being equipped with a pair of-spaced apart electrical contacts mountedto project into said one chamber for engagement by said plate to close said contacts,the improvement wherein:

said diaphragm plate comprises a disc element defining a resiliently flexible tongue projecting laterally thereof and away from the diaphragm, and defining a projecting end portion, and means cooperating between said tongue end portionand said housing to cause said tongue to act as a range spring while resiliently spacing said disc element from said contacts whereby 'said disc element closes said contacts under predetermined pressure differentials in said chambers.

2. The improvement set forth in claim 1 wherein said means cooperating between said tongue end portion and said housing comprises:

an adjustment screw threadedly mounted in said housing and being in operative engagement with said tongue end portion. 3. A differential pressure switch, said switch comprismg:

a pair of matched housing sections secured together in face to face relation to form a housing,

a diaphragm interposed and clamped between said sections,

said sections each being recessed on either side of said diaphragm to define fluid pressure chambers on either side of said diaphragm of restricted depth,

said sections each defining a bore in communication with said chambers thereof that is adapted for communication to a source of fluid pressure,

a diaphragm plate received in one of said chambers and seated on one side thereof against said diaphragm,

said diaphragm plate comprising a disc element. of electrically conductive material defining a tongue projecting laterally thereof and defining a projecting end portion,

with the housing section that defines said one chamber being equipped with a pair of spaced apart electrical contacts projecting into said one chamber for engagement by said disc element to close said contacts,

said contact equipped housing section having a range spring adjustment screw threadedly mounted in same that extends crosswise of said diaphragm plate and is journalled at one end of same in said tongue projecting end portion,

whereby said adjustment screw may adjust said tongue to act as a range spring for said diaphragm plate to set said plate against said diaphragm whereby said disc element closes said contacts under predetermined pressure differentials in said chambers. I

4. The pressure switch set forth in claim 3 wherein:

said chambers are round in outline in the plane of said diaphragm,

. said disc element being round in circumferential configuration,

said tongue includng a tab off set from the axial center of said disc and in keying relation to said housmg. v

5. The pressure switch set forth in claim 4 wherein:

said tongue tab is received in an indentation formed in said contact equipped section.

6. The pressure switch set forth in claim 3 wherein:

said contact equipped housing section chamber is the low pressure chamber of said switch and the chamber of the other housing section is the high pressure chamber of the switch,

said recess of said other housing section defining a generally planar end wall surface of said high pressure chamber that is spaced laterally of said diaphragm to make said high pressure chamber of shallow proportions transversely of said diaphragm, 4

said other housing section including spaced bosses on said recess wall thereof of restricted dimension laterally of said diaphragm to maintain said diaphragm spaced frorn saidrecess wall for application to pressures in said high pressure chamber to the full area of said diaphragm that is exposed to said high pressure chamber.

7. The pressure switch set forth in claim 3 ,wherein:

said housing is quadrilateral in configuration in the plane of said sections,

said sections each defining matching openings at the corners thereof,

with at least some of said openings of the respective housing sections including interengaging means,

and means for riveting said housing sections together thorugh said openings.

8. The pressure switch set forth in claim 3 wherein:

the other end of said screw is exposed exteriorly of said housing,

said screw other end being recessed within said housand means for keying said connectors relative to said housing against rotational movement with respect thereto. i

10. A differential pressure switch of miniaturized proportions, said switch comprising:

a pair of matched housing sections of relatively small proportions secured together in face to face relation to form a housing,

a diaphragm interposed and clamped between said sections and substantially coextensive therewith, said sections each being recessed on either side of said diaphragm to define fluid pressure chambers of circular shape and of restricted depth on either side of said diaphragm,

said sections each defining a bore in communication with said chambers thereof that is adapted for communication to a source of fluid pressure,

a round diaphragm plate received in one of said chambers and seated on one side thereof against said diaphragm,

said diaphragm plate comprising a disc element of electrically conductive material defining a tongue projecting laterally thereof and defining a projecting end portion,

with the housing section that defines said one chamher being equipped with a pair of spaced apart electrical contacts projecting into said one cham-' ber for engagement by said disc element to close said contacts,

said contact equipped housing section having a range spring adjustment screw threadedly mounted in same that extends crosswise of said diaphragm plate and is journalled at one end of same in said tongue projecting end portion,

said tongue including a tab offset from the axial center of said disc and connected in keying relation to said housing,

said housing sections and said diaphragm defining UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO; 5 ,5 7 e Dated January 975 Inventor(s) James Phillips and Richard S. Zoludow It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line +2, "to" should be of Eigncd and Scaled this seventh Day'of ocm ermu [SEAL] Attest':

RUTH C. MASON I CJIARSHALL DANN FORM P0-1050 (10-69) 1 USCOMM-DC coan U.S. GOVIIINMENT PRINTING OFFICE: 9 9 o- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,862,587 Dated January 1975 Inventor(s) James Phillips and Richard S. Zoludow It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line A2, "to" should be of Signed and Scaled this 0 sevnth Day of 0-ct0'ber1975 [SEAL] Attest:

. RUTH C. MASON C. MARSHALL ANN Anesling Officer Commissioner oj'latents and Tradema FORM Po-105O (10-69) USCOMM-DC 60376-P69 US. GOVERNMENT PRINTING OFFICE: 9 o 

1. In a differential pressure switch of the type including a housing having a diaphragm therein defining with said housing fluid pRessure chambers on either side of said diaphragm of restricted depth, with said housing defining bores in communication to separate sources of fluid pressure, and an electrically conductive diaphragm plate received in one of said chambers and seated on one side thereof against said diaphragm, with the housing portion that defines said one chamber being equipped with a pair of spaced apart electrical contacts mounted to project into said one chamber for engagement by said plate to close said contacts, the improvement wherein: said diaphragm plate comprises a disc element defining a resiliently flexible tongue projecting laterally thereof and away from the diaphragm, and defining a projecting end portion, and means cooperating between said tongue end portion and said housing to cause said tongue to act as a range spring while resiliently spacing said disc element from said contacts whereby said disc element closes said contacts under predetermined pressure differentials in said chambers.
 2. The improvement set forth in claim 1 wherein said means cooperating between said tongue end portion and said housing comprises: an adjustment screw threadedly mounted in said housing and being in operative engagement with said tongue end portion.
 3. A differential pressure switch, said switch comprising: a pair of matched housing sections secured together in face to face relation to form a housing, a diaphragm interposed and clamped between said sections, said sections each being recessed on either side of said diaphragm to define fluid pressure chambers on either side of said diaphragm of restricted depth, said sections each defining a bore in communication with said chambers thereof that is adapted for communication to a source of fluid pressure, a diaphragm plate received in one of said chambers and seated on one side thereof against said diaphragm, said diaphragm plate comprising a disc element of electrically conductive material defining a tongue projecting laterally thereof and defining a projecting end portion, with the housing section that defines said one chamber being equipped with a pair of spaced apart electrical contacts projecting into said one chamber for engagement by said disc element to close said contacts, said contact equipped housing section having a range spring adjustment screw threadedly mounted in same that extends crosswise of said diaphragm plate and is journalled at one end of same in said tongue projecting end portion, whereby said adjustment screw may adjust said tongue to act as a range spring for said diaphragm plate to set said plate against said diaphragm whereby said disc element closes said contacts under predetermined pressure differentials in said chambers.
 4. The pressure switch set forth in claim 3 wherein: said chambers are round in outline in the plane of said diaphragm, said disc element being round in circumferential configuration, said tongue includng a tab off set from the axial center of said disc and in keying relation to said housing.
 5. The pressure switch set forth in claim 4 wherein: said tongue tab is received in an indentation formed in said contact equipped section.
 6. The pressure switch set forth in claim 3 wherein: said contact equipped housing section chamber is the low pressure chamber of said switch and the chamber of the other housing section is the high pressure chamber of the switch, said recess of said other housing section defining a generally planar end wall surface of said high pressure chamber that is spaced laterally of said diaphragm to make said high pressure chamber of shallow proportions transversely of said diaphragm, said other housing section including spaced bosses on said recess wall thereof of restricted dimension laterally of said diaphragm to maintain said diaphragm spaced from said recess wall for application pressures in said high pressure chamber to the full area of said diaphragm that is exposed to said Pressure chamber.
 7. The pressure switch set forth in claim 3 wherein: said housing is quadrilateral in configuration in the plane of said sections, said sections each defining matching openings at the corners thereof, with at least some of said openings of the respective housing sections including interengaging means, and means for riveting said housing sections together thorugh said openings.
 8. The pressure switch set forth in claim 3 wherein: the other end of said screw is exposed exteriorly of said housing, said screw other end being recessed within said housing and hex socketed for application thereto of a turning means.
 9. The pressure switch set forth in claim 3 including: a pair of electrical connectors applied to said contact equipped housing section and each including a planar end seated against said contact equipped housing section, said contacts each comprising rivet means anchoring the respective connectors to said housing in electrical conducting relation thereto, and means for keying said connectors relative to said housing against rotational movement with respect thereto.
 10. A differential pressure switch of miniaturized proportions, said switch comprising: a pair of matched housing sections of relatively small proportions secured together in face to face relation to form a housing, a diaphragm interposed and clamped between said sections and substantially coextensive therewith, said sections each being recessed on either side of said diaphragm to define fluid pressure chambers of circular shape and of restricted depth on either side of said diaphragm, said sections each defining a bore in communication with said chambers thereof that is adapted for communication to a source of fluid pressure, a round diaphragm plate received in one of said chambers and seated on one side thereof against said diaphragm, said diaphragm plate comprising a disc element of electrically conductive material defining a tongue projecting laterally thereof and defining a projecting end portion, with the housing section that defines said one chamber being equipped with a pair of spaced apart electrical contacts projecting into said one chamber for engagement by said disc element to close said contacts, said contact equipped housing section having a range spring adjustment screw threadedly mounted in same that extends crosswise of said diaphragm plate and is journalled at one end of same in said tongue projecting end portion, said tongue including a tab offset from the axial center of said disc and connected in keying relation to said housing, said housing sections and said diaphragm defining matching openings about the margin of said housing, with at least some of said openings of the respective housing sections including interengaging means including means for locating said diaphragm relative to said sections on assembly thereof, whereby said adjustment screw may adjust said tongue to act as a range spring for said diaphragm plate to set said plate against said diaphragm whereby said disc element closes said contacts under predetermined pressure differentials in said chambers. 